Whirling Disease

[sandeel]

I recieved the following from Trout Unlimited today..... pay special note to the section on Marlyand Infected water....

thanks,


Whirling disease poses a major threat to trout across Maryland.

Here are a few easy steps you can take to prevent the spread of this disease:

1. Do not move fish from one stream to another
2. Do not discard trout carcasses in streams, or on stream banks
3. Please be sure to clean mud from boots and equipment before moving from one stream to another
4. Clean all boats and kayaks and do not transport water from one area to another

Whirling disease is caused by a parasite and once it establishes itself in a stream or a host fish population it cannot be eradicated.

While it poses no known danger to humans, it damages cartilage, especially in young fish, making it impossible for them to swim normally to seek food and escape predators. It is always fatal.

This disease can completely decimate a trout population and ruin your favorite stream.

MARYLAND
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Already this year the state Department of Natural Resources (MD DNR) has had to destroy 156,000 infected fish.

In Maryland, the organism is known to exist in the North Branch of the Potomac River, Sand Run, and Bear Creek. So anglers should pay particular attention when moving from those streams to other areas. It may be present in other parts of the state as well.

But the good news is that by taking the precautions listed above, you can help end this outbreak.
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Trout Unlimited has published two national reports on Whirling disease where you can learn more:

Whirling Disease in the United States: A Summary of Progress in Research and Management

Given that whirling disease is now present in half of all states in the US, the advice on prevention in Maryland is also applicable to anglers everywhere—so tell your friends across the country about how to stop the spread.

A brochure put out by Montana State University is full of information concerning the disease as well as a fact sheet that you can keep in your wallet for future reference. Both are available on our website.

Thank you for doing all you can to stop this deadly disease.

Wishing you good fishing,

Joseph McGurrin
Trout Unlimited

[Salmo trutta]

It's been documented on the N. Branch since the 90's. They only use N. Branch raised fish to stock the N. Branch and the fish are still reproducing. I've never seen sick looking fish while fishing it. But it's there and we should be careful about our gear and never take a fish or sediments from there to another stream.

[Jeffrey Rasband]

How is it in the N. Branch but not the Savage river tailwater? Fish freely move beetween the two rivers so wouldnt the virus distribute accordingly? just curious.

[spilunkr]

Jeff,

It may be in the Savage but at much lower levels. But there are not many rainbows in the Savage to begin with so the effects of the disease would be less noticeable. Whirling Disease requires an intermediate host; in this case tubifex worms. Since moving out here to Colorado, I have learned more about Whirling Disease than I did back in MD.

Apparently, the particular specie of tubifex worm responsible for the disease does not do particularly well in high gradient well oxygenated streams. That is why for instance although the disease is present in the Big Thompson River here it has not had much of an affect on the rivers population of Rainbow trout, (brown trout are fairly resistent and brookies are intermediate in response betwen rainbows and browns). The Savage below the reservoir is much higher in gradient than the N. Branch.

Also CDOW has some interesting studies that seem to indicate that many strains of tubifex worms do not transmit the disease at all. They have had some success in supressing the population of the carrier tubifex worms by introducing large numbers of non-carrier strains. CDOW has been able to supress the carrier population to levels low enough that rainbows were able to be successfully reintroduced to watersheds where they had been severely affected.

Guy